Structure for sealing a watch crystal in a waterproof watch

ABSTRACT

A watch crystal is sealed into a watch by means of an annular gasket of a relatively hard material such as a synthetic resin or soft metal. The parts comprising the seal are so dimensioned that the crystal seats in the gasket in an interference fit and the gasket fits in the case body in an interference fit. Such gaskets, while providing an effective seal even when subjected to high pressure, have long life, and hold the crystal sufficiently strongly so that a bezel is not needed.

United States Patent Fujimori [45] July 18, 1972 [54] STRUCTURE FORSEALING A WATCH 254,004 4/1948 Switzerland ..58/91 CRYSTAL IN AWATERPROOF WATCH 282,140 4/1952 Switzerland ....58/90 R 296,071 l/l954Switzerland ..58/9] Inventor: Ymhhki Fujimori, Suwa, Japan 343,9482/1960 Switzerland ..58/91 73 A K b kl ssrgnee Jalaulshl Kaisha SuwaSeikosha, Tokyo, Primary Examiner stephen J Tomsky AssistantExaminerGeorge H. Miller, Jr. [22] Filed: Aug. 16, 1971 Attorney-AlexFriedman et al. [2!] App]. No.: 171,871 [57] ABSTRACT A A watch crystalis sealed into a watch by means of an annular Q Foreign ApplicationPriority Data gasket of a relatively hard material such as a syntheticresin or Aug: [7, 1970 Japan ..45/71598 soft metal. The parts comprisingthe seal are so dimensioned 4 that the crystal seats in the gasket in aninterference fit and the [52] US. Cl. ..58/90 R, 58/91 gasket fits inthe case body in an interference fit. Such gaskets, [5 1] Int. Cl...G04b 37/08, G04b 39/00 while providing an effective seal even whensubjected to high [58] Field of Search ..58/90 R, 91, 105 pressure, havelong life, and hold the crystal sufficiently strongly so that a bezel isnot needed. [56] References Cited 7 Clams, 3 Drawing figures FOREIGNPATENTS OR APPLICATIONS 846,977 6/1952 Germany ..-..s8/91 STRUCTURE FORSEALING A WATCH CRYSTAL IN A WATERPROOF WATCH BACKGROUND OF THEINVENTION In conventional constructions for sealing a watch crystal intoa waterproof watch, a relatively soft gasket is inserted between thecrystal and the case body. Where such soft gaskets are used, it isnecessary to provide a bezel to prevent disengagement of the glass fromthe case body. In such a construction, the packing is deformed to aconsiderable extent, particularly where it is to be maintained inwaterproof condition against relatively high pressure. Under such circumstances, the packing is apt to cold-flow and deteriorate so that themaintenance of the waterproof condition is of relatively shortduration.

The use of a bezel increases the cost of the watch and has disadvantageswith respect to design. In order to avoid these disadvantages, attemptshave been made to use materials which are harder than rubber. However,these have not been successful because the gasket material has beenfound to break or to deform excessively during assembly.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas been found to be possible to use gasket materials harder than rubberby proper design of the pertinent components, namely the watch crystal,the gasket and the interior of the case body.

To effect a waterproof seal between the watch crystal and the gasket,the gasket, which is annular, has a frustoconical interior surface intowhich the watch crystal can be inserted to form an interference fit.Similarly, the interior of the case body also has a frustoconical innersurface into which the gasket, holding the watch crystal, can beinserted to form an interference fit. The gasket, preferably, is made ofa synthetic resin or a soft metal. The watch crystal, the exterior ofthe gasket and the interior of the case body may be provided with guidesurfaces to facilitate assembly. The dimensions of the components can bematched to the hardness of the gasket so that the watch crystal may beof an inorganic glass without encountering the problem of breakageduring assembly.

Accordingly, an object of the present invention is to provide astructure for sealing a watch glass to a waterproof watch where thestructure will have long life.

Another object of the invention is to provide a structure for sealing awatch glass to a waterproof watch while eliminating the need for abezel.

A further object of the invention is to provide a structure for sealinga watch crystal to a waterproof watch where the assembly must withstandhigh pressure.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of theinvention, reference is had to the following description taken inconnection with the accompanying drawing, in which:

FIG. 1 is a cross sectional view of a gasket in accordance with thepresent invention;

DESCRIPTION OF PREFERRED EMBODIMENTS A gasket I1 is shown in FIG. 1prior to assembly. The gasket I1 is essentially L-shaped with lower arm12 having an inner base 12 which is planar. Angle 6 between peripherallip 13 and inner base 12' is less than 90 is subject to a furtherrestriction which will be described below.

Watch crystal 14 also has a planar base 15 designed to seat againstinner base 12 of gasket 11. Angle 6 between the base 15 of watch crystall4 and periphery 16 of the watch crystal is such that upper arm 17 ofgasket 11 is deformed outwardly during insertion of the watch crystal.To form an effective seal, angle 0 must be larger than angle 6,. Angle0, may suitably lie in the range of about to and preferably is 9020 Theamount by which angle 0, is less than 0 will depend on the hardness anddeformability of gasket 1 I. As part of the gasket design, outer surface18 of upper arm 17 is so shaped that when the watch crystal is insertedin the gasket, outer surface 18 will become cylindrical in shape.

To effect a tight seal between gasket 11 and case body [9, angle 0between inner bottom 21 and inner periphery 22 of case body 19 is madeless than 90. The inner periphery 22 of case body 19 is frustoconicaland has a minimum diameter in the plane indicated in FIG. 3 by thereference letters xx. As can be seen, the plane of the minimum circleintersects periphery 16 of the watch crystal.

To facilitate assembly of the structure, watch glass 14 is provided witha guide surface 23, gasket 11 is provided with an exterior guide surface24 and case body 19 is provided with an interior guide surface 25.

It is important in order to achieve proper sealing that the innersurface 13 and the exterior surface 17 of gasket 11 be smooth in finish.The same is true of inner periphery 22 of case body 19. The innerperiphery 22 is preferably finished with a buff cloth. The outer surface18 of gasket 11 can be rendered cylindrical by finishing while deformedby the watch crystal.

In forming the guide surface 24, the plane at its maximum diametershould lie within the lower arm 12, i.e., below the plane of inner base12. The distance between these two planes is indicated by the referenceletter b in FIG. 1 and is not critical. By locating the maximum circleof the guide surface 24 within the lower arm 12, pressure on the watchglass 14 during assembly of the gasket into the case body 19 is avoided.

Suitable materials for the gasket 1 l are synthetic resins such aspolycarbonate and ABS resin. The gasket may also be made of a soft metalsuch as copper or silver.

Despite the fact that relatively hard gaskets of synthetic plastic orsoft metal are used in the present structure, forces on the watchcrystal are compressive and symmetrical. Consequently, the watch crystalmay be of inorganic glass and yet the assembly operation can be carriedout without breaking said crystal.

The structure disclosed herein, using a gasket of synthetic resin orsoft metal, and with interference fits between watch crystal and gasketand case body provides resistance to the entry of water for long periodsof time while eliminating problems of breakage during assembly.Moreover, since the necessity for a bezel is eliminated, the structureis simplified and cost of the final watch is decreased.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in the above construction withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description or shown in theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:

1. A structure for sealing a waterproof watch comprising a watch glasshaving a base perpendicular to the axis of said glass and a peripherymaking an angle 0 with said base of said glass, and annular gaskethaving an inner base perpendicular to the axis of said gasket and aninner peripheral lip making an angle 6 with said inner base, where isless than 0, and the dimensions of said glass and said gasket are suchthat said glass can be seated firmly against the inner base and theinner peripheral lip of said gasket by deforming said gasket outwardly,the outer surface of said gasket being cylindrical when said gasket isdeformed by said glass, and a metallic case body having an inner bottomagainst which said gasket can be firmly seated and a frustoconical innersurface tapering inwardly away from said inner bottom, said innersurface having a circle of minimum diameter dimensioned for receivingsaid gasket in an interference fit, the plane of said circle of minimumdiameter intersecting said periphery of said glass.

2. The structure of claim 1, wherein 0, lies between 90 and about 85.

3. The structure ofclaim 1, wherein said glass is inorganic.

4. The structure of claim 1, wherein said glass has a frustoconicalguide surface to facilitate insertion of said glass into said gasket.

5. The structure of claim 1, wherein said gasket has an exteriorfrustoconical guide surface to facilitate insertion of said gasket intosaid case body, and said case body has an interior frustoconical guidesurface to facilitate the insertion of said gasket into said case body.

6. The structure of claim 1, wherein said gasket is of a materialselected from the group consisting of synthetic resin and a soft metal.7

7. The structure of claim 6, wherein said synthetic resin is selectedfrom the group consisting of polycarbonate and ABS.

1. A structure for sealing a waterproof watch comprising a watch glasshaving a base perpendicular to the axis of said glass and a peripherymaking an angle 1 with said base of said glass, and annular gaskethaving an inner base perpendicular to the axis of said gasket and aninner peripheral lip making an angle theta 2 with said inner base, wheretheta 2 is less than theta 1 and the dimensions of said glass and saidgasket are such that said glass can be seated firmly against the innerbase and the inner peripheral lip of said gasket by deforming saidgasket outwardly, the outer surface of said gasket being cylindricalwhen said gasket is deformed by said glass, and a metallic case bodyhaving an inner bottom against which said gasket can be firmly seatedand a frustoconical inner surface tapering inwardly away from said innerbottom, said inner surface having a circle of minimum diameterdimensioned for receiving said gasket in an interference fit, the planeof said circle of minimum diameter intersecting said periphery of saidglass.
 2. The structure of claim 1, wherein theta 1 lies between 90* andabout 85*.
 3. The structure of claim 1, wherein said glass is inorganic.4. The structure of claim 1, wherein said glass has a frustoconicalguide surface to facilitate insertion of said glass into said gasket. 5.The structure of claim 1, wherein said gasket has an exteriorfrustoconical guide surface to facilitate insertion of said gasket intosaid case body, and said case body has an interior frustoconical guidesurface to facilitate the insertion of said gasket into said case body.6. The structure of claim 1, wherein said gasket is of a materialselected from the group consisting of synthetic resin and a soft metal.7. The structure of claim 6, wherein said synthetic resin is selectedfrom the group consisting of polycarbonate and ABS.